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# M1 - Connected Particles Question watch

1. Hi I'm wondering if somebody would be able to help me with this question, cant get my head around it...

Two particles of masses 6m and m are attached to the ends A and B of a light inextensible string which passes over a smooth pulley C at the top of a fixed rough plane inclined at 300 to the horizontal. The particles are at rest with the 6m mass in contact with the plane and the mass m hanging freely so that AC is along the greatest slope of the plane and BC is vertical.

1) Find the frictional force between the 6m and the plane (3 marks).
2) Find the range of values for the coefficient of friction for equilibrium to be possible. (4 Marks)

Many Thanks
2. (Original post by SuperHuman10)
Hi I'm wondering if somebody would be able to help me with this question, cant get my head around it...

Two particles of masses 6m and m are attached to the ends A and B of a light inextensible string which passes over a smooth pulley C at the top of a fixed rough plane inclined at 300 to the horizontal. The particles are at rest with the 6m mass in contact with the plane and the mass m hanging freely so that AC is along the greatest slope of the plane and BC is vertical.

1) Find the frictional force between the 6m and the plane (3 marks).
2) Find the range of values for the coefficient of friction for equilibrium to be possible. (4 Marks)

Many Thanks
start by drawing a diagram

3. That is my diagram. Do I need to form sim equations or resolve vertically?

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4. (Original post by SuperHuman10)

That is my diagram. Do I need to form sim equations or resolve vertically?

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good start

firstly when the particles move, equilibrium is broken
can you find an expression for the friction by resolving perpendicular to the plane?
5. R = 6mg x cos(30)

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6. (Original post by SuperHuman10)
R = 6mg x cos(30)

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correct

so you now have an expression for the friction.

next 2 separate equations of motion for each object

PS:If you are replying please use the reply with quote button otherwise I cannot see you unless I refresh the screen
7. (Original post by TeeEm)
correct

so you now have an expression for the friction.

next 2 separate equations of motion for each object

PS:If you are replying please use the reply with quote button otherwise I cannot see you unless I refresh the screen
But there are two unknowns? The coefficient of friction and friction?

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8. (Original post by SuperHuman10)
But there are two unknowns? The coefficient of friction and friction?

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T= friction
T = mg
9. (Original post by TeeEm)

T= friction
T = mg

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10. (Original post by SuperHuman10)

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you are correct

I do not have the picture in front of me

T=mg from the hanging object

T = friction +6mgsin30

then you find friction (as a total)

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